Recovery of condensate water from AHS

The condensate water from air handling stations (AHS) has been identified as a source of water that can be recovered as part of Changi’s water recycling efforts. Six AHS at Terminal 2 have been designed so that condensate water will be recovered and pumped to top-up the makeup water of the cooling towers. 

As NEWater – Singapore’s high-grade treated used water – forms a significant share of the source of water used for operational consumption, the recovery of condensate water from the AHS would reduce the need to utilise fresh NEWater for the cooling towers. The condensate recovery will enable CAG in saving over 60,000 cubic metres of water annually, which is equivalent to the volume held by 24 Olympic-sized swimming pools.

Upgrading cooling tower water treatment systems

Traditional cooling tower water treatment is reliant on the use of chemicals to mitigate bacteria growth, scaling, and other water quality issues. While these chemical treatment methods are effective in maintaining water cleanliness, they necessitate regular dilution and disposal to manage chemical concentration, often resulting in significant water consumption.

In pursuit of a more sustainable alternative, the Terminal 4 (T4) integrated Facilities Management (iFM) team embraced an innovative treatment system which utilises Electro-Chemical Activation (ECA). This advanced technology mirrors the beneficial effects of traditional treatment, but in an eco-friendlier manner. It functions by producing oxidising chemicals through the electrolysis of water, effectively managing water quality and controlling bacteria and other contaminants without the use of harsh chemicals. Additionally, the system incorporates an electrolytic water softening process that extracts calcium and magnesium ions from the water. This reduces the need for dilution and disposal to manage chemical concentration, thereby avoiding excessive water usage.

A crucial benefit of this system is its impact on cycles of concentration (COC) — a measure that indicates how many times water can be re-used before it needs to be replaced. By enhancing the COC, the system reduces the frequency of water flush-outs, enabling the cooling tower to operate more efficiently and use less water. This approach has led to a 16% reduction in cooling tower water consumption in T4.

By implementing the ECA system, CAG has enhanced operational efficiencies and reduced environmental impact, aligning with its sustainability goals. Importantly, these advancements have been achieved while fully complying with regulatory water quality standards, ensuring that its operations remain sustainable and compliant.